The present invention relates to data acquisition and measurement, and in particular to an expansion plug apparatus for connecting multiple terminal blocks in a data acquisition or measurement device chassis.
Currently most engineers and scientists use personal or industrial computers (PCs) with expansion buses for laboratory research, industrial control, test, and measurement systems. Such systems may be referred to generally as Data Acquisition (DAQ) systems. Typically, such systems include a personal or industrial host computer, one or more transducers, signal conditioning logic or software, measurement hardware, and software. Transducers convert physical phenomena into electrical signals. For example, thermocouples and thermistors convert temperature into a voltage or resistance, respectively. Other examples of transducers include strain gauges, flow transducers, and pressure transducers, which convert force, rate of flow, and pressure to electrical signals, respectively.
In many DAQ systems, the DAQ hardware is comprised on a card installed in the host computer. Cables may couple the DAQ hardware directly to sensors, transducers, or a Unit Under Test (UUT), or to intervening hardware such as a signal conditioning device, which is in turn coupled to the UUT.
Transducer outputs must often be conditioned by signal conditioning logic to provide signals suitable for input to a measurement device. Signal conditioning logic may take many forms, including dedicated switching modules, or conditioning logic built into the measurement device, e.g., digital multimeters and probes used with oscilloscopes. Signal conditioning logic or software may amplify low-level signals, isolate, filter, excite, and/or provide bridge completion to produce appropriate signals for the measurement device.
Measurement hardware typically includes a signal digitizer which is operable to receive analog signals from one or more transducers or signal conditioners, and convert the analog signals into digital form via sampling.
DAQ systems generally include software as well, such as driver software and application software. DAQ system driver software typically comprises a software library that directly programs the registers of the measurement hardware, managing its operation and its integration with computer resources, such as processor interrupts, direct memory access (DMA), and memory. Driver software hides the low-level, complicated details of hardware programming while preserving high performance. Application software provides an efficient way to program measurement hardware. One exemplary system used to develop application software is National Instruments"" LabVIEW graphical programming environment. Application software may add analysis and presentation capabilities to the driver software, and may also integrate instrument control, such as GPIB (General Purpose Instrument Bus), RS-232, PXI, and VXI, with computer-based measurement components.
Many DAQ hardware systems, including signal conditioning devices, typically take the form of one or more modules in a chassis. Each module typically interfaces to an external signal source, such as a transducer or UUT, through a terminal block. A terminal block provides a convenient method for connecting and disconnecting I/O signal wires or cables to a DAQ system. More specifically, a terminal block provides a simple and convenient interface to an individual module in a chassis through which wires or cables from one or more signal sources or other devices may be coupled.
Some DAQ tasks may require a great number of I/O connections, for example, to receive input from a great number of signal sources. In other words, it may be necessary to connect a large number of wires or cables to the data acquisition, measurement, or signal conditioning hardware, thereby exceeding the number of connections available for a given terminal block. Typically, in these cases, multiple terminal blocks/modules may be xe2x80x9cdaisy-chainedxe2x80x9d together via patch wires or cables, thereby forming a single integrated xe2x80x9csuper-modulexe2x80x9d. For example, when each terminal block/module pair comprises a switching matrix, one or more of the terminal blocks may be daisy-chained together, thereby integrating the corresponding switch matrices together to form a single integrated switch matrix which is capable of receiving a great number of I/O connections. Furthermore, the integrated switch matrix facilitates the routing of signal paths to and from any of the corresponding modules from and to any of the interconnected terminal blocks.
However, when the number of input wires or cables and the number of interconnected modules are great, the wiring requirements become increasingly complex. Such complexity increases the chance for wiring errors during setup, and greatly increases the time and effort required to configure and re-configure the system. Furthermore, the use of many patch wires or cables presents a confusing and messy or unclean interface. Therefore, improved systems and methods are desired for interconnecting a plurality of terminal blocks.
A system and method for connecting multiple terminal blocks in a data acquisition or measurement device chassis are presented. According to one embodiment of the invention, an expansion plug may be adapted to connect the multiple terminal blocks. The expansion plug may include a housing which has a rectangular form factor, with at least two connectors comprised on one side of the expansion plug. In other embodiments the expansion plug may have other form factors, such as a square, oval, or any other suitable form factor. The expansion plug may have a shallow profile which accommodates rack-mount installation of the chassis in that no extra vertical rack space is required for the expansion plug.
In one embodiment, the expansion plug may include a first connector and a second connector which are electrically connected to each other, and which may be operable to couple the expansion plug to two adjacent terminal blocks. In a preferred embodiment, the first connector and the second connector are disposed on a first surface of the expansion plug housing.
In one embodiment, a first terminal block and an adjacent second terminal block may be coupled together by the expansion plug. Each of the terminal blocks includes at least one plug connector which is operable to couple to one of the two connectors of the expansion plug. In one embodiment, the first terminal block may comprise a first plurality of column connections, and the second terminal block may comprise a second plurality of column connections. The expansion plug may electrically couple the first terminal block to the second terminal block wherein each of the first plurality of column connections is electrically coupled to a corresponding one of the second plurality of column connections. Thus, the expansion plug may couple the first and second terminal blocks via the respective column connections of each terminal block.
In another embodiment, the first terminal block may comprise a first plurality of row connections, and the second terminal block may comprise a second plurality of row connections. The expansion plug may electrically couple the first terminal block to the second terminal block wherein each of the first plurality of row connections is electrically coupled to a corresponding one of the second plurality of row connections. Thus, the expansion plug may couple the first and second terminal blocks via the respective row connections of each terminal block.
In one embodiment, the plug connectors of the first and second terminal blocks may comprise top plug connectors which are located on a top edge of the terminal blocks. In this embodiment, the first connector of the expansion plug couples to the top plug connector of the first terminal block; and the second connector of the expansion plug couples to the top plug connector of the second terminal block.
In one embodiment, the second terminal block may also include a bottom plug connector. In one embodiment, the bottom plug connector may be substantially identical to the top plug connector, but located on the opposite, or bottom, edge of the terminal block. Furthermore, a third terminal block may also include a bottom plug connector, wherein a first connector of a second expansion plug may be operable to couple to the bottom plug connector of the second terminal block, and a second connector of the second expansion plug may be operable to couple to the bottom plug connector of the third terminal block. Thus, the second expansion plug may be operable to electrically couple the second terminal block to the third terminal block via the respective bottom plug connectors of each terminal block.
In a preferred embodiment, each terminal block may include both a top plug connector and a bottom plug connector so that each terminal block may be coupled to a neighboring terminal block via an expansion plug using either top plug connectors or bottom plug connectors.
In one embodiment, each terminal block may implement at least a portion of a switch matrix, such that the first terminal block implements at least a portion of a first switch matrix, and the second terminal block implements at least a portion of a second switch matrix. The expansion plug may be operable to electrically couple the portion of the first switch matrix to the portion of the second switch matrix to form at least a portion of a third switch matrix, wherein the portion of the third switch matrix comprises at least a portion of an integrated switch matrix comprising the portions of the first and second switch matrices.
In one embodiment, the chassis may be operable to receive a plurality of switching modules into respective slots of the chassis. In one embodiment, one or more of the plurality of switching modules may comprise signal conditioning modules. In one embodiment, a plurality of terminal blocks may each be operable to couple to respective ones of the plurality of switching modules. In one embodiment, each terminal block/switching module pair may comprise a switching matrix, such that the first terminal block and the first switching module together comprise a first switch matrix, the second terminal block and the second switching module together comprise a second switch matrix, and so on.
A plurality of expansion plugs may couple each adjacent pair of terminal blocks in the manner described above. More specifically, the first expansion plug may electrically couple the first switch matrix to the second switch matrix to form the third switch matrix, wherein the third switch matrix comprises the integrated switch matrix comprising the first and second switch matrices. Similarly, the second expansion plug may electrically couple the second terminal block (with the second module) and the third terminal block (with the third module), thereby integrating the switch matrix comprised by the third terminal block and module into the integrated third switch matrix.
It should be noted that in the preferred embodiment, successive terminal block pairs are coupled via top and bottom plug connectors in an alternating manner. For example, the first terminal block may be coupled to the second terminal block via top plug connectors, the second terminal block may be coupled to the third terminal block via bottom plug connectors, the third terminal block may be coupled to the fourth terminal block via top plug connectors, and so on. Thus, in one embodiment, the plug connector pairs used to couple consecutive pairs of terminal blocks may alternate in a top, bottom, top, bottom, etc., manner. Thus, any number of terminal block/module pairs may be coupled together via expansion plugs in an interleaved manner, such that a plurality of switch matrices corresponding to a plurality of terminal block/switching modules may be integrated into a single integrated switch matrix.
Thus, using the system described above, a plurality of terminal blocks (with corresponding switching modules) may be coupled together via expansion plugs until a switch matrix of the desired size is formed.